The present invention relates to a particulate support matrix, to rapidly dissolving pharmaceutical dosage forms made therefrom, and to processes of preparing such a support matrix and such a dosage form.
The recent, current and projected growth of the elderly population in the U.S. and abroad is well recognized. Currently, 12% of the U.S. population is 65 years of age or older and receives nearly 30% of the medications prescribed. It is anticipated that there may be a 10% to 60% increase in the demand for drugs by the elderly under some new government programs. In spite of the disproportionately large demand for prescription pharmaceuticals among the elderly, relatively little attention has been directed to meeting the unique pharmacotherapeutic needs of this age group. Drug products are currently designed for three groups of individuals: infants, pediatrics and adults. The needs of the infants are obviously different from those of children 2 to 12 years of age and the needs of children are obviously different from those of adults. However, the needs of the elderly population are being overlooked as they have special characteristics that necessitate dosage forms designed especially for them. Many older patients have difficulty swallowing tablets or capsules and yet the vast majority of dosage forms administered to the elderly are tablets or capsules. Uncoated tablets are convenient and economical to manufacture but are often difficult to swallow and often cause discomfort by "hanging" in the throat. Coated tablets and capsules are somewhat easier to swallow but with increasing age and the large number of drug products that are administered to a single individual, this is a source of apprehension. Liquid dosage forms are relatively easy to administer but are more costly, easily spilled, often do not taste good, occupy large volumes of space per dosage unit, and possess some inherent stability problems. As is evident, the needs of the elderly differ from those of other populations and deserve special attention in new drug development, product formulation, posology, product packaging, product labeling, patient information, and product marketing and sales. A practical and new dosage form would be of value for these patients.
Pediatric patients generally have difficulty swallowing until they reach the age of about 10-16 years old. Younger pediatric patients generally take either chewable tablets, crush and mix regular tablets with food/juice, or take a liquid dosage form. Chewable tablets, generally a good dosage form, do not always taste good. Crushing and mixing regular tablets with food or juice, is time-consuming, messy and not always practical. The difficulty of liquid dosage forms, i.e., syrups, is that they are bulky, do not always taste good, and that drugs are not as stable in a liquid dosage form as they are in a solid dosage form, such as a tablet. A practical and new dosage form would also be of value for these patients.
Incarcerated patients often will retain their medications within the oral cavity while pretending to swallow them. These can then be accumulated and taken all at once for an enhanced drug effect. Obviously, this can be very dangerous. A dosage form which would not remain intact once placed in the oral cavity would be useful when treating these patients.
There are currently several fast-dissolving products on the market. These products have a number of drawbacks including the manufacturing methods used, taste masking, and pre- versus post-loading techniques that are required. One commercially available dosage form is prepared by a lyophilization, or freeze-drying, technique which is slow and expensive. Because each "batch" of material must be handled in its entirety, the tablet cannot be produced using a continuous process where raw materials come in and finished product is output at the other end. This tablet can be either pre-loaded (i.e., the drug is added to the tablet matrix before the tablet is formed) or post loaded (the drug is added after the tablet "blank" is prepared).
One difficulty with a freeze-dried dosage form is that of taste masking. To effectively mask the taste of poorly tasting drugs, it is generally necessary to micro-encapsulate or nano-encapsulate them. Then, if they are pre-loaded, the encapsulating shell material may dissolve during the tablet production process allowing the drug to leak into the tablet matrix, resulting in a poorly tasting product. If the tablet is post-loaded, the tablet may become disfigured causing the tablet to be disposed of or handled again, adding extra expense to the process.
Another commercially available dosage form is prepared using solid state dissolution techniques. These manufacturing methods are expensive and add additional cost to the tablet. This tablet must be post-loaded. This is necessary because drugs are generally soluble in the water and alcohol which is used in the preparation of the tablet. As with the freeze-dried dosage form discussed above, when a solution of the drug is post-loaded onto the matrix blank, often the tablets become disfigured. Another problem encountered with the solid state dissolution technique is the selection of a solvent material that will evaporate quickly but will not attack the microcapsule shell surrounding the active drug.
Effervescent dosage forms contain substantial percentages of compounds for enhancing tablet breakup and dissolution which may also serve to mask the taste of certain medications. These tablets depend upon approximate stoichiometric quantities of sodium bicarbonate and an acid, e.g., citric acid or tartaric acid, reacting to form CO.sub.2 to break up the tablet in the mouth. The difficulty with the commercially available effervescent tablets is that the mouth tends to "foam" leaving an uncomfortable feeling to many.